This invention relates to intraocular lenses (IOLs). More particularly, the invention relates to intraocular lenses which provide accommodating movement in the eye.
The human eye is susceptible to numerous disorders and diseases, a number of which attack the crystalline lens. For example, cataracts mar vision through cloudy or opaque discoloration of the lens of the eye, and can result in partial or complete blindness. When this happens, the crystalline lens can be removed and replaced with an intraocular lens, or IOL. A typical IOL comprises an optic body, or lens, adapted to focus light toward the retina of the eye, and one or more fixation members, or haptics, adapted to secure the IOL in a relatively fixed position in a suitable location such as the anterior chamber, iris, or capsular bag of the eye.
The optic and haptics may be formed as an integral unit from a single material, but in recent years the trend has been toward composite IOLs which use different materials for the various components, so that the properties of these components can be separately optimized. Examples of such composite IOLs are shown in Barrett U.S. Pat. No. 4,997,442 and Vanderbilt U.S. Pat. No. 5,217,491, both of which employ relatively flexible materials in the optic portion and more rigid materials in the haptics. The disclosure of each of these patents is incorporated in its entirety herein by reference.
One drawback of conventional IOLs has been that, while they provide suitable correction for normal distance vision, they do not provide effective accommodation, i.e. the ability to refocus the eyes as needed for viewing both near and distant objects. Until fairly recently, the only solution was to wear eyeglasses, but other options are now available. For instance, multifocal IOLs have been designed for providing near, far, and intermediate vision. In addition, IOLs have been provided with movement assemblies which cooperate with the ciliary muscles and/or other structures of the eye to move the optic axially between near and far vision positions. Examples of this latter class of IOLs, referred to broadly as accommodating IOLs, can be found in Levy U.S. Pat. No. 4,409,691, Cumming U.S. Pat. Nos. 5,674,282 and 5,496,366, Gwon et al. U.S. Pat. No. 6,176,878, Lang et al. U.S. Pat. No. 6,231,603, and Laguette et al. U.S. Pat. No. 6,406,494. The disclosure of each of these patents is incorporated in its entirety herein by reference.
The aforementioned references are concerned primarily with the geometry and mechanical configuration of various accommodating IOLs, but deal only cursorily, if at all, with material selection and manufacturing issues. Certain general properties of the IOL components such as, for instance, flexibility of the movement assembly, are described as being preferred or desirable, but are not delineated in absolute or relative terms.
It is an object of this invention, accordingly, to design an accommodating IOL from an appropriate combination of materials which provide optimum optical qualities, increased accommodation ability, and, preferably, sufficient flexibility to allow the IOL to be inserted through a small incision in an eye.
A further object of the invention is to provide methods for manufacturing the IOLs.